Agriculture Reference
In-Depth Information
Fig. 16.1
Arsenic uptake and metabolism and detoxification in plants. The thickness of arrow
lines is indicative of the relative flux. Transporters for arsenic uptake into leaf cells are assumed
to be similar to those in roots, but there is little knowledge of their identities. (Source: Zhao et al.
2010
4 Arsenic Metabolism
Studies involving different plant species have shown the predominance of arsenite
in plant tissues accounting > 90 % of total arsenic, which indicates that once arse-
nate finds its way in plants, it is reduced to arsenite (Zhao et al.
2009
). Further,
plant tissue extracts show arsenate reduction activity (Duan et al.
2007
). In agree-
ment with this, plant homologues of yeast
Acr2p
have been isolated in
Arabidopsis
(Dhankher et al.
2006
),
H. lanatus
(Bleeker et al.
2006
),
O. sativa
(Duan et al.
2007
), and
P. vittata
(Ellis et al.
2006
). Interestingly, plant ACR2 but not yeast
Acr2P and PvACR2 show additional tyrosine phosphatase activity that may have a
role in cell cycle regulation (Ellis et al.
2006
; Landrieu et al.
2004
a; Landrieu et al.
2004
b). Plants with ACR2 proteins expressed in a heterologous system, also show
reduction of arsenate in-vitro using GSH and glutathione as reductants. However,
